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HMRC letter codes · National Insurance (CA)

CA307Refund of UK National Insurance paid while working abroad

Last reviewed 14 October 2026 · How Tax Letters checks its facts

In short

GOV.UK lists the CA307 as the form to apply for a refund of UK National Insurance contributions paid while working abroad.

“Apply for a refund of UK National Insurance contributions paid while working abroad (CA307)”

GOV.UK: Apply for a refund of UK National Insurance contributions paid while working abroad (CA307) · checked 14 October 2026

Information, not advice: this page reports what HMRC, GOV.UK and the bodies named publish about CA307. Each fact has its source and the day it was checked beside it.

What it asks

GOV.UK's CA307 page says you will need to tell HMRC information about your employment abroad, the date you left the UK and the country you were in.

“To apply you will need to tell us: … information about your employment abroad … the date you left the UK … the country you were in”

GOV.UK: Apply for a refund of UK National Insurance contributions paid while working abroad (CA307) · checked 14 October 2026

GOV.UK's CA307 page says you need to fill in the print and post form fully before you can print it, and that you cannot save a partly completed form.

“You’ll need to fill in the print and post form fully before you can print it. You cannot save a partly completed form”

GOV.UK: Apply for a refund of UK National Insurance contributions paid while working abroad (CA307) · checked 14 October 2026

How to send it or apply

GOV.UK's CA307 page says that to claim such a refund you can use the online form service or fill in the form on-screen, print and post it to HMRC.

“To claim a refund of UK National Insurance contributions paid while working abroad, you can either: … use the online form service … fill in the form on-screen, print and post to HMRC”

GOV.UK: Apply for a refund of UK National Insurance contributions paid while working abroad (CA307) · checked 14 October 2026

GOV.UK's CA307 page says you need to sign in to claim online, and that you can create sign in details if you do not already have them.

“You’ll need to sign in to claim online. If you do not already have sign in details, you’ll be able to create them.”

GOV.UK: Apply for a refund of UK National Insurance contributions paid while working abroad (CA307) · checked 14 October 2026

Free help and HMRC contacts

If you have a question about refunds of National Insurance contributions, such as one about CA307, GOV.UK’s National Insurance enquiries page says to call HMRC on 0300 200 3500. Lines are open Monday to Friday, 8am to 6pm, and the page links to “Find out about call charges”.

“Call HMRC for help and information with: … refunds for National Insurance contributions … Telephone: 0300 200 3500 … Opening times: Monday to Friday, 8am to 6pm. … Find out about call charges”

GOV.UK: National Insurance: enquiries · checked 14 October 2026

Free help first

These routes are described by GOV.UK, TaxAid and Citizens Advice themselves.

  • HMRC's extra supportHMRC offers extra support if your health condition or personal circumstances make it difficult to contact HMRC, for example a mental health condition, financial hardship or being treated in hospital.
  • Someone to deal with HMRC for youYou can authorise a friend, relative or voluntary organisation to talk to HMRC for you and help you fill in forms.
  • TaxAidTaxAid helps people with tax problems who cannot pay for advice. Tax Help for Older People merged with TaxAid in July 2025.
  • Citizens AdviceCitizens Advice gives confidential advice online, over the phone and in person, for free.